The Ancient Greek philosophers Plato, Cratylus and Pyrrho as well as Roman philosopher Sextus Empiricus are among those who expounded theories of radical skepticism.
Pyrrho |
Pyrrho, Greek philosopher from Elis, credited as being the first skeptic philosopher and inspiration for the school known as Pyrrhonism (b. c. 360 BC)
Diogenes Laertius (ix.61) relates that he was a student of Pyrrho, along with Eurylochus, Timon the Phliasian, Nausiphanes of Teos and others, and includes him among the "Pyrrhoneans".